Cerridwen provides geocentric planetary data suitable for a broad spectrum of astronomical and astrological applications, with a focus on our solar system. Among its data you will find, for example, the time of the next sunrise or that of the last full moon, or simply the current tropical position of the sun. It comes with a simple command-line utility and a JSON server, but is also designed to serve as a basis for your own application.

TRIP is a general computer algebra system dedicated to celestial mechanics. It includes a numerical kernel and has interfaces to gnuplot and xmgrace. Computations can be performed with double, quadruple, or multi-precision. Users can dynamically load external libraries written in C, C++, or Fortran. Parallel computations on multivariate polynomials can be performed.

INDI is an instrument-neutral distributed
interface control protocol that aims to provide
backend driver support and automation for a wide
range of astronomical devices (telescopes,
focusers, CCDs, etc.). Current supported devices
include many telescopes, CCDs, filter wheels,
focusers, and video cams. INDI is used in popular
astronomy suites like Xephem, KStars, DCD, and Cartes
Du Ciel.

Lynkeos processes astronomical webcam images. By
stacking the best images, the signal to noise
ratio is increased, and details lost in the noise
of individual images become visible in the
resulting image. This software accepts, as input,
QuickTime, AVI, and MPEG sequences, or still images, in any image format supported by its active plugins (TIFF, FITS) and Cocoa. It generates a 16-bit RGB TIFF or a monochrome FITS image as output, to be further processed with some all-purpose image processing application.

CFITSIO is a library of C and Fortran subroutines for
reading and writing data files in the FITS (Flexible Image
Transport System) data format. It simplifies the task of
writing software that deals with FITS files by providing an
easy to use set of high-level routines that insulate the
programmer from the internal complexities of the FITS file
format.